African Americans Twice As Likely To Have Clogged Leg Arteries

Being African American can double your risk of developing clogged leg arteries – a condition called peripheral artery disease (PAD), according to a study inCirculation: Journal of the American Heart Association.

“Our study found that African-American ethnicity was a strong and independent risk factor for peripheral arterial disease,” said lead author Michael H. Criqui, M.D., M.P.H., professor of medicine and professor of family and preventive medicine at the University of California, San Diego School of Medicine.

In PAD, arteries outside of the heart and brain – most often the legs – become clogged by cholesterol-rich plaque. The classic complaint is intermittent claudication – painful cramping in the hips, thighs or calves that occurs during exercise and eases a few minutes after stopping. When the leg blockage is severe, pain is more constant. Severe PAD can also slow the healing of wounds to the feet and, in severe cases, may lead to amputation.

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PAD is a marker for atherosclerosis elsewhere in the body. An estimated eight million Americans have PAD.

Criqui suggested that physicians be alert to the possibility of PAD in African Americans.

“Physicians decide which patients to check carefully for PAD based on their age and other risk factors,” he said. “This research says that physicians need to be particularly alert to the possibility of PAD in their African-American patients. Their independent increased risk is as high as someone in another ethnic group 10 years older, or someone their own age who smoked a pack of cigarettes for 20 years.”

Researchers examined 2,343 people, ages 29 to 91, for the presence of PAD. They compared rates among members of four ethnic groups – 1,401 non-Hispanic whites, 322 African Americans, 341 Asians and 279 Hispanics. Most were randomly chosen from current or retired employees of the University of California San Diego and their spouses, and most participants had health insurance and access to medical care.

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Previous studies of ethnicity and PAD underestimated the occurrence of the disease by classifying people as unaffected if they currently showed good circulation but had previously undergone surgery to unblock a clogged artery, Criqui said.

In this study, researchers used Doppler ultrasound to measure blood pressure in the leg arteries, and compared blood pressure readings taken in the ankles with those in the arms (the ankle-brachial index) to look for a deficit in lower-limb circulation. People were considered to have PAD in any of three circumstances:

blood pressure in the ankles was less than 90 percent of the arm measurements;

blood pressure in the leg arteries was abnormal;

or they previously had surgery for PAD;

Overall, there were 104 cases of PAD. Men (6.1 percent) were more likely to be affected than women (3.6 percent). The rates of PAD increased sharply with age, roughly doubling for each decade from 1.2 percent for those age 50 and younger to 10.2 percent for those age 70 or older.

In the ethnic group comparisons, researchers found PAD in 7.8 percent of African Americans, 4.9 percent of non-Hispanic whites, 1.8 percent of Hispanics and 1.4 percent of Asians.

“We did not have enough Hispanic or Asian participants to definitively exclude any ethnic differences in PAD, but there did not seem to be a pronounced difference,” Criqui said.

Several factors significantly raised the risk of PAD in the study — diabetes, hypertension, cigarette smoking, a ratio of high total cholesterol to low HDL cholesterol and a history of cardiovascular disease. After controlling for these factors, African Americans had 2.34 times the risk of non-Hispanic whites.

To determine whether the higher incidence of PAD in African Americans might be related to less vigorous treatment of cardiovascular risk factors, the researchers examined medication records. They found that African Americans with high blood pressure or high cholesterol were just as likely to be taking medication for these conditions as participants in other ethnic groups.

“It had been presumed that the excess of PAD in African Americans was due to a greater proportion of African Americans having diabetes and hypertension,” Criqui said. “Even though we found a link with those conditions, we were surprised that they only explained part of the risk. For reasons that are still unclear, something related to African-American ethnicity raises the risk of PAD.”

The research was supported in part by the National Heart, Lung, and Blood Institute and the American Heart Association.

Editor’s Note: The American Stroke Association, a division of the American Heart Association, is launching Power To End Stroke – a movement to aggressively reach African Americans, who are at highest risk for stroke. For information about Power To End Stroke, call 1-888-4-STROKE or visit strokeassociation.org.

Statements and conclusions of study authors that are published in the American Heart Association scientific journals are solely those of the study authors and do not necessarily reflect association policy or position. The American Heart Association makes no representation or warranty as to their accuracy or reliability.